Method of making a jig for beading of color electron gun assemblies



Aug. 18," 4 s. J owsK ETAL 3,524,492 METHOUOF MAKING A J 16 FOR BEADING OF COLOR 1 ELECTRON GUN ASSEMBLIES Filed Dec. 18, 1967 SEYMOUR JANOWSKY, HAROLD SKURN'K, I JOHN runow INVEN TORS.

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ATTORNEYS United States Patent O METHOD OF MAKING A JIG FOR BEADING F COLOR ELECTRON GUN ASSEMBLIES Seymour Janowsky, Clifton, Harold Skurnik, Bloomfield,

and John Turow, West Paterson, N.J., assiguors to Aiken Industries, Inc., Superior Electronics Company (a division of Aiken Industries, Inc.), Clifton, N.J., a corporation of Delaware Filed Dec. 18, 1967, Ser. No. 691,503 Int. Cl. B22d 19/00 US. Cl. 164-98 7 Claims ABSTRACT OF THE DISCLOSURE A method of making a jig for holding a color electron gun assembly for beading so that the axes of the guns converge at a predetermined angle includes the steps of providing a casting jig with spaced apart locating plates having axial parallel holes therein, positioning casting pins in the holes on an angle to the axis equal to the angle of convergence of the guns with the casting pins contacting the side edges of the axial parallel holes. Then a bushing is placed on the end of each casting pin, a sleeve is positioned around the bushings, and material 1s cast in the space between the sleeve and bushings resulting in an article having bushings extending in precise directions for holding the electron guns during their mechanical assembly.

BACKGROUND OF THE INVENTION This invention relates to improvements in the making of jigs, especially jigs having holes which must converge or diverge at a precise angle. The invention is especially useful for making jigs for beading electron guns.

Electron gun assemblies utilizing three converging guns are used in great numbers in cathode ray tubes for color television receivers. In the common commercially used gun assembly there are three separate guns positioned adjacent one another around a central axis. The axes of the guns converge so that an electron beam passing through the apertures of the electrodes in the electron gun converge at a precise angle. The assembly of electrodes for each of the three guns is rigidified by glass beads applied to the outside edge of the electrodes. There are three beads applied to a three gun assembly as is known in the art.

In order to hold the three electron guns in a precisely predetermined position for beading while their axes converge toward each other at a very precise angle, e.g. between 50' of arc and one degree, it is common to use a jig. The jig receives three pins on which the electrodes of each gun have been assembled and axially aligned. Accordingly, the jig has three holes in it equally spaced around a central axis and converging at the required precise angle. To provide a jig having these holes bored accurately therein at the precision angles required is usually difiicult and expensive.

SUMMARY OF THE INVENTION This invention overcomes the defect of the prior art in making a jig for this purpose simply and inexpensively without substantial setup or boring costs. Furthermore the jig of this invention can be rapidly made when a change in the angle of convergences is required.

In general, this invention includes providing a casting jig and positioning casting pins in the casting jig with the casting pins corresponding to the pins on which the electrode or electron guns are assembled. The casting pins in the casting jig are accurately referenced to the particular precision angle of a convergence by a pair of ICC spaced apart plates having parallel axially bored holes therein. The holes in one of the plates are closer to the center of the plate than those of the other plate so that the casting pin will be at the required angle when it contacts the edge surfaces of radially aligned holes of both plates. Since the holes are drilled parallel and axially there is very little setup, tooling, or drilling expense. After the casting pins are positioned in the holes, bushings are placed around an extending end of the casting pins, a sleeve placed to loosely surround all the bushings, and the space between the sleeve and bushings is filled with a casting material. It has been found that use of this invention reduces the cost and expense of making a jig for assembling an electron gun by a factor of five.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in connection with a preferred example illustrated in the accompanying drawings in which:

FIG. 1 is a sectional view of a jig of the prior art.

FIG. 2 is a longitudinal sectional view of a jig made in accordance with this invention.

FIG. 3 is an exploded view illustrating making of the jig in accordance with this invention, showing. the components in section where appropriate.

FIG. 4 is a longitudinal sectional view of a portion of the components shown in FIG. 3.

FIG. 5 is a diagrammatic view illustrating the positioning of casting pins in the methodof this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates the prior art jig for holding electron guns of the type used in color TV tubes. With color electron gun assemblies there are three separate guns which are mounted together in a unitary assembly by glass or ceramic beads applied along the side edges of the gun assembly. The unitary assembly has the axes of the guns converging at a small but precision angle. In the prior art, electrodes of the electron guns are assembled on pins 10 which then align the electrodes of each gun for the heading operation by positioning pins 10 within holes 12 precision bored into a jig block 14. The jig block 14 may be only a portion of a larger jig assembly for use in a beading operation. It is however a very important part since the alignment and position of holes 12 in the ji-g block 1 determines the alignment of the electron guns. Further, since the holes 12 are not parallel and axial but are on a slight angle, it is very difiicult and expensive to accurately drill these holes with respect to a longitudinal axis. In other words, with the center axis of pin 1 extending at an angle a to the longitudinal center line of the jig block and gun, the expenses of setting up and boring or drilling holes 12 in jig block 14 are quite high.

This invention contemplates a method of making a beading pin holder 16'as shown in FIG. 2 or any other similar article wherein alignment of bores at critical precision angles is difiicult and expensive. The method is practised utilizing a casting jig 18, FIG. 3. The casting jig has a cylindrical body 20 with an end ring 22 secured thereto by screws 24 and end cap 26 secured thereto by screws 28. A pair ofplates 30 and 32 are positioned in contact with the inner surface of ring 22 and cap 26 and the plates are spaced apart by an inner sleeve 34. Inner sleeve 34 has slots 36 and 38 cut therein and radially aligned with one another for referencing pins 40 and 42 of the end plates 32 and 30, respectively. These pins and the slots 36 and 38 align plates 30 and 32 in a circumferential direction. This is necessary to radially align holes such as holes 44 and 46 in the plates. These holes are shown schematically in FIG. 5. They are bored axially so that the walls of the holes are parallel with the longio inal center axis L in FIG. 5. Casting pins 48 and 50 are of the same diameter as beading pins on which the electrodes of the electron guns are assembled. There are three of the casting pins although only two are shown in the sectional view of FIG. 3.

The holes 44 and 46 in the plates 30 and 32 are chosen such that when casting pin 48 is positioned in a hole it will abut against the outer edge corner 52 and the inner edge corner 54 of hole 46 and similarly abut against the inner edge corner 56 and outer edge corner 58 of the hole 44. These edge corners cooperating with the rigid pin 48 define the angle the axis of the pin 48 extends to the central axis in a very precise manner with extremely low tolerances. Of course the distance plates 30 and 32 are spaced apart together with the radial distance of the holes 44 and 46 are drilled from the center line L and the diameter of the holes with respect to the diameter of the casting pin 48 determine the angle of pin 48 with respect to the central axis. These parameters can be calculated as required to determine the angle of convergence for the particular electron guns being beaded. If there is a change in angle of convergence of the electron guns all that needs to be changed in the present casting jig are the plates 30 and 32 to put other plates in having the required different arrangement of holes.

'After the casting pins 48, 50 and another, not shown, have been placed in the holes so they converge toward the central axis at a precisely predetermined angle, bushings 64, 66 are slipped on over the ends of the casting pins 48 and 50 as shown in FIG. 4 and a sleeve 60 is placed in the cap 26 so that this lower edge 62 abuts the cap as shown in FIG. 4. This will still leave a space 68 between the outer periphery of the bushings 64, 66 and the inner periphery of sleeve 60. A solid material 70 such as a low melting metal alloy which has no shrinkage or expansion during hardening is cast in space 68 to make a rigid assembly of the beading pin holder 16 as shown in FIG. 2.

The outer periphery of each beading pin holder bushing is provided with an undercut groove 72 and the inner periphery of the sleeve 60 has an undercut groove 74 for interlocking with the cast material 70. The bushings 64 and 66 are of cast iron and have a precision bored inner surface 76 which then receives the electrode holders 10 for beading as is known in the art. The beading pin holder 16 of this invention may be just a portion of an entire jig for holding the assembled electrodes, but the other portions of the jig are conventional and merely clamp the assembly together.

As can be seen applicant has disclosed a unique method of making a beading pin holder for holding pins of color electron guns for the beading operation in a precisely predetermined position extending at an angle to the axis. The holder can be made quickly and inexpensively since it does not require any holes to be drilled and at an angle to the axis, as all holes including holes 44 and 46 are drilled parallel with the axis.

Utilizing the teachings of this invention significant savings for the cost of manufacturing of electronic guns has been made. This invention can be applied to any device with non-parallel bores and is not necessarily limited to jigs for beading color electron guns.

While the invention has been particularly shown and described with reference to a preferred embodiment there- 4 of, it will be understood by those skilled in the art that various changes in form and details may be made there in without departing from the spirit and scope of the invention.

We claim:

1. A method of making a device having at least one bore therein which is positioned at a precision acute angle not parallel to the axis of the device, the method comprising; providing a casting jig with fixed spaced apart locating plates having holes therethrough parallel to the longitudinal axis of the jig, the holes in one plate being closer to the longitudinal axis of the casting jig than those of the other plate positioning at least one casting pin through holes in the plates the pin extending at an angle to the longitudinal axis of the jig equal to a predetermined precise angle, the casting pin contacting the edge surfaces of the axial holes in the fixed spaced apart plates for positive location, placing a bushing on the casting pin, positioning a sleeve around the bushing, casting a material into the space between the sleeve and bushing, and removing the casting jig so that the sleeve, bushing, and cast material provide a rigid device with at least one nonparallel bore at the required precision angle.

2. A method as in claim 1 wherein there are at least two holes in each plate to accommodate at least two casting pins which in turn receive at least two bushings.

3. A method as defined in claim 2 further comprising referencing the plates of the casting jig circumferentially so that the axial holes of the spaced apart plates are in radial alignment.

4. A method as in claim 3 further comprising interlocking the cast material to the sleeve and bushings.

5. A method as in claim 4 wherein the casting material is a low melting point metal alloy which has insignificant shrinkage or expansion during hardening.

6. A method as in claim 5 wherein there are three casting pins, and three corresponding bushings.

7. A method of making a jig for holding electrodes for use in the beading of color electron guns, the method comprising providing a casting jig having fixed spaced apart locating plates with holes therethrough parallel to the longitudinal axis of the jig, there being three holes in each plate radially aligned, the holes in one plate being closer to the center of the plate than those of the other plate, positioning casting pins of a lesser diameter than the holes through the radially aligned holes in both plates, the casting pins contacting the edges of the holes adjacent to the surfaces of the plates and thereby extending at an angle to the longitudinal axis of the casting jig equal to the angle of convergence of the electrodes of the electron gun assembly, placing a bushing on each of the casting pins and a sleeve around the bushings leaving a space between the bushing and the sleeve, casting within the space between the bushing and the sleeve a solid material, and removing the rigid assembly of the sleeve, cast material and bushing forming a beading pin holder from the casting jig.

References Cited UNITED STATES PATENTS 3,399,440 9/1968 Blumenberg et al. 29-25.19 X

I. SPENCER OVERHOLSER, Primary Examiner V. K. RISING, Assistant Examiner US. Cl. X.R. 

